1. Technical Field of the Invention
The present invention relates to an electronic flexible circuit connector and, in particular, to a flexible circuit connector formed through a single layer of flexible polymeric film substrate without the use of solder to mechanically fasten and electrically connect a male connector to the substrate.
2. Description of Related Art
A flexible circuit includes a flexible dielectric substrate having conductive inks printed on the substrate surface to define circuit traces. The dielectric substrate typically comprises a polymeric film and in particular a polyimide film. Components are attached to be flexible circuit with component connectors either passing through apertures in the flexible circuit or being seated on land pads etched into the substrate. The electrical contacts of these components are typically soldered in electrical contact with the aperture or the land to mechanically secure the component to the flexible circuit.
The characteristics of the dielectric substrate permit a flexible bending of the substrate to accommodate locating the flexible circuit in applications where a non-rigid printed circuit is required. However, care must be taken in shaping the dielectric film or the production of any holes through the material since any irregularities in the edges of the dielectric film can easily lead to tearing of the flexible circuit damaging the circuit beyond repair. Consequently, connections made with the circuit traces to interface devices operating with the flexible circuit are typically made by running the traces to an edge surface of the flexible connector and attaching a ribbon connector to the traces by soldering leads in the ribbon connector to the traces. This is a factor to be considered when creating a circuit trace layout design for the flexible circuit. The ribbon connectors typically have a pin socket at the other end for attachment to the interface device.
While the use of through hole connection of terminals to dielectric substrates has been achieved with printed circuit boards, it should be understood that these printed circuits typically comprise several layers of polyimide film separated by layers of insulation resulting in a rigid substrate having a thickness in the order of 0.062 thousands of an inch. One such through hole connector is disclosed in U.S. Pat. No. 5,172,472 issued Dec. 22, 1992 to Linder et al. where a multi-layer rigid printed circuit board fabrication method is disclosed. In this patent, a hexagonal shaped pin is forced through several layers of a mylar film material having intermittent insulation layers and a printed circuit core or substrate. The hexagonal shaped pin has a diameter greater than the diameter of the layers of mylar material and equal to the diameter of the core of the printed circuit core. As the pin is forced through the openings, its cuts and deforms the flexible mylar layers into wiping contact with the pin. In order to cut into the mylar layers without tearing the layers, the rigid core and intermittent layers of insulation between the mylar layers are required, otherwise it would not be probable to obtain a wiping electrical contact.
U.S. Pat. No. 5,548,488 issued Aug. 20, 1996 to Scott Hansen discloses use of an electrical lamp socket mounted to a rigid substrate with a flexible circuit sandwiched between the socket and the rigid substrate. The flexible circuit carries electrical traces having conductive terminals with central apertures formed having a slightly smaller diameter than corresponding aligned apertures in the rigid supporting substrate. The lamp socket includes two elongate terminal pins which pass through the aligned apertures of the flexible circuit and the rigid substrate to deform the aperture of the flexible circuit against the rigid substrate. Mechanical fastening of the lamp socket component is made between the terminal pins of the lamp socket component and rigid substrate. Due to the sensitivity of the dielectric flexible substrate to tearing, the supporting substrate is necessary in order to mechanically secure the terminal pins and two prevent tearing of the flexible circuit.
There is a need to develop a direct connection of a terminal to a flexible circuit that does not require a solder paste to mechanically secure the terminal to the flexible circuit, ensures good electrical contact with the circuit and allows for increased circuit trace design flexibility over the use of ribbon connectors.